Mars Pathfinder

Airbag Retraction and Lander Righting

Once the Mars Pathfinder lander has settled on
the surface, pyrotechnic devices in the lander petal latches are blown to
allow the petals to be opened. The latches locking the sturdy side petals
in place are necessary because of the pulling forces exerted on the lander
petals by the deployed airbag system.

In parallel with the petal latch release, a retraction
system will begin slowly dragging the airbags toward the lander, breaching
vent ports on the side of each bag, in the process deflating the bags through
a cloth filter. The airbags are drawn toward the petals by internal lines
extending between attachments within the airbags and small winches on each
of the lander sides. It takes about 64 minutes to deflate and fully retract
the bags.

There is one high-torque motor on each of the three
petal hinges. If the lander comes to rest on its side, it will be righted
by opening a side petal with a motor drive to place the lander in an upright
position. Once upright, the other two petals are opened.

About 3 hours is allotted to retract the airbags
and deploy the lander petals. In the meantime, the lander's X-band radio
transmitter will be turned off for the first time since before launch on
December 4, 1996. This saves battery power and will allow the transmitter
electronics to cool down from being warmed up during entry without the cooling
system. It also allows time for the Earth to rise well above the local horizon
and be in a better position for communications with the lander's low-gain
antenna later in the morning.